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Biomedical subjects

S Oki

Publications and source records attributed to S Oki.

At least 109 records · Page 6Linked to original sources
PubMed1985

[A scanning electron microscopical and morphometrical analysis of neuromuscular junctions in different muscle fiber types in the zebra finch and rat].

The differences of neuromuscular junctions (NMJs) between different muscle fibers had been examined with scanning electron microscopy and analyzed morphometrically. The anterior and posterior latissimus dorsi muscles of the zebra finch were compared. The former consisted exclusively of slow tonic fibers and the latter of fast twitch fibers. The former had numerous, small NMJs. The synaptic depressions were small in number. The latter had a large NMJ. The synaptic depressions were large in number, and subsynaptic folds were found. The extensor digitorum longus and soleus muscles in the rat were also compared. The former consisted mostly of fast twitch fibers whereas the latter consisted of slow twitch fibers (75%) and fast twitch fibers (25%). NMJ of slow twitch fiber was small and the subsynaptic folds had sparse, narrow slit-like and pit-like openings. NMJ of fast twitch fiber was large and the subsynaptic folds had numerous, wide and slit-like openings.

Animals↗
PubMed1984

A case report of pancreatic metastasis of an intracranial angioblastic meningioma (hemangiopericytoma) and a review of metastatic tumor to the pancreas.

The authors report a case of solitary metastasis to the pancreas from an intracranial angioblastic meningioma (hemangiopericytoma) and discuss secondary (metastatic) tumors of the pancreas. A 65-year-old man developed a pancreatic tumor 15 years after the craniotomy was performed for a parasagittal meningioma. Histological investigation of the pancreatic tumor excised as a biopsy on exploratory laparotomy revealed a tumor identical to the intracranial meningioma. It was concluded that the intracranial angioblastic meningioma had recurred and metastasized to the pancreas.

Aged↗
PubMed1983

Biosynthesis and distribution of opioid peptides.

Group III opioid peptides are derived from proenkephalin B. The processing of this precursor peptide is still only partly understood and we still do not know how many final products come from proenkephalin B and whether Leu-enkephalin is produced from Group III peptides. However, potent biologic activity of Group III opioid peptides and existence of opiate-receptors specific for these peptides (k receptors) strongly suggest that Group III opioid peptides are not precursors of Leu-enkephalin but bioactive substances per se. Further studies should clarify details of the processing of proenkephalin B.

Adrenal Medulla↗
PubMed1983

gamma 1-Melanotropin-like immunoreactivity in bovine and human adrenocorticotropin-producing tissues.

gamma 1 MSH-like immunoreactivity in bovine pituitary glands, hypothalami, human pituitary glands, ectopic ACTH-producing tumors, and human gastric antral mucosa was investigated using a newly developed RIA for gamma 1 MSH. The minimum detectable quantity of gamma 1 MSH was 3 pg/tube, and the antibody did not cross-react with gamma 2 MSH, gamma 3 MSH, alpha MSH, beta MSH, ACTH, beta-lipotropin, or beta-endorphin. Bovine anterior pituitary, intermediate-posterior pituitary, and hypothalamus contained more than two molecular weight forms of gamma 1 MSH-like immunoreactivities. On the other hand, gamma 1 MSH-like immunoreactivity was not detected in human pituitary glands or human gastric antral mucosa, but was detected in one of seven ectopic ACTH-producing tumors. These results suggest a limited processing of the ACTH-beta-lipotropin precursor to gamma 1 MSH in human tissues, although a rapid degradation of gamma 1 MSH could not be ruled out completely.

Adrenocorticotropic Hormone↗
PubMed1983

Experimental microsurgical embolectomy after middle cerebral artery embolization in the dog.

The effects of microsurgical embolectomy were investigated clinicopathophysiologically in 60 dogs after occlusion of the middle cerebral artery (MCA) trunk with a silicone cylinder embolus. One group of animals served as a control (non-embolectomized group), and in the other two groups the embolus was removed 3 or 6 hours after occlusion (3-hour or 6-hour embolectomy group). In the non-embolectomized animals, major neurological deficits with deep cerebral infarction were observed. Regional cerebral blood flow (CBF) in the basal ganglia decreased most prominently. Sensory evoked potentials also declined to about 50% of the control level 3 hours after embolization. In the 3-hour embolectomy group, mild neurological deficits with minimal infarctions were found. One hour after embolectomy, CBF was restored to the original level in all regions, and the sensory evoked potentials surpassed the control level. In the 6-hour embolectomy group, most animals exhibited major neurological deficits and severe brain swelling with hemorrhagic infarction. This study suggests that early microsurgical embolectomy of the MCA trunk restores blood flow in the perforating arteries and prevents deep cerebral infarction.

Animals↗
PubMed1982

Characterization of gamma-melanotropin-like immunoreactivity and its secretion in an adrenocorticotropin-producing mouse pituitary tumor cell line.

gamma MSH, a putative hormone in the N-terminal region of the ACTH/beta-endorphin (beta-EP) precursor protein, was studied by RIA with an antiserum against gamma 3MSH in ACTH-producing mouse pituitary tumor cells, AtT-20/D16v. Serial dilution of the culture medium or the cell extract gave parallel lines to the standard curve in the RIA for gamma MSH. Rat median eminence extracts enhanced the release of gamma MSH-like immunoreactivity (gamma MSH-LI) concomitant with ACTH-like immunoreactivity (ACTH-LI) and beta-EP-like immunoreactivity (beta-EP-LI). Dexamethasone suppressed the release of gamma MSH-LI as well as ACTH-LI and beta-EP-LI. Gel exclusion chromatography of the culture medium and the cell extract has revealed that gamma MSH-LI consists of two peaks; one eluted near the elution position of beta-lipotropin and the other near the elution position of beta-EP. There was no peak corresponding to the elution position of synthetic gamma 3MSH. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) has demonstrated that gamma MSH-LI migrated at five positions with molecular weights of 31K, 21-23K, 16-17K, 13-14K, and 3.8K, respectively. The 31K gamma MSH coincided with the migration position of 31K ACTH of 31K beta-EP, and 21-23K gamma MSH coincided with the position of 21-23K ACTH on SDS-PAGE. The 16-17K gamma MSH coincided with the mouse 16K fragment (reported by Eipper and Mains) of ACTH-beta-lipotropin precursor protein in the migration in SDS-PAGE and in immunoreactivity to anti-gamma MSH antiserum. [3H]Glucosamine was incorporated into 16K, 13K, and 3.8K gamma MSH. These results suggest that AtT-20/D16v cells produce gamma MSH-LIs with molecular weights of 31K, 21-23K, 16-17K, 13-14K, and 3.8K, and they are secreted concomitantly with ACTH-LI and beta-EP-LI.

Adrenocorticotropic Hormone↗
PubMed1982

Presence of immunoreactive gamma-melanocyte-stimulating hormone, adrenocorticotropin, and beta-endorphin in human gastric antral mucosa.

gamma MSH-like, ACTH-like, and beta-endorphin-like immunoreactivities (gamma MSH-LI, ACTH-LI, and beta-endorphin-LI, respectively) were detected in water extracts of four human gastric antral mucosa. The concentrations of gamma MSH-LI, ACTH-LI, and beta-endorphin-LI in the boiling water extracts were 9.9 +/- 3.3, 6.2 +/- 1.8, and 3.9 +/- 1.3 ng/g (mean +/- SE), respectively. Gel exclusion chromatography on a Bio-Gel P-60 column showed that most ACTH-LI and beta-endorphin-LI were eluted at the elution positions of human ACTH and beta-endorphin, respectively. The major peak of gamma MSH-LI was eluted at the elution position of big gamma MSH-LI, but another peak was eluted at the elution position of small gamma MSH-LI, as in bovine intermediate pituitary. Concanavalin A-agarose affinity chromatography showed that 52% of gamma MSH-LI was specifically bound to the column, but only 8% of ACTH-LI and none of beta-endorphin-LI were specifically bound. These results suggest that there exists an ACTH/beta-lipotropin common precursor protein in human antral mucosa and that the processing of the precursor is accelerated as a bovine intermediate pituitary, indicating possible roles of these peptides in the function of the gastrointestinal tract.

Adrenocorticotropic Hormone↗
PubMed1981

Presence of dynorphin-like immunoreactivity in rat pituitary gland and hypothalamus.

Using a highly specific and sensitive radioimmunoassay for dynorphin(1-13), dynorphin-like immunoreactivity (dynorphin-LI) was detected in rat pituitary and hypothalamus. Gel chromatographic studies on Sephadex G-50 revealed three components of dynorphin-LI with molecular weights of approximately 7500-9500 (big dynorphin), 3500-5500 (intermediate dynorphin) and 1600-1900 (small dynorphin), the latter of which eluted at the same position as authentic dynorphin contamination in porcine ACTH extracts (Sigma). Dynorphin-LI in rat anterior pituitary existed mainly as big dynorphin, whereas dynorphin-LI in rat intermediate-posterior pituitary and hypothalamus eluted mainly at the position of authentic small dynorphin.

Animals↗
PubMed1981

Gamma-melanotrophin-like immunoreactivities in human pituitaries, ACTH-producing pituitary adenomas, and ectopic ACTH-producing tumours: evidence for an abnormality in glycosylation in ectopic ACTH-producing tumours.

Using gel exclusion chromatography on Bio-Gel P-60, gamma-melanotropin-like immunoreactivity (gamma-MSH-LI) in three human pituitary glands, two ACTH-producing pituitary adenomas, and three ectopic ACTH-producing tumours (two medullary thyroid carcinomas and one thymoma) was divided into one or two molecular weight classes. The largest component eluted near the position of mouse 16K fragment and was designated big gamma-MSH-LI. This big gamma-MSH-LI was present in all samples. The second one, designated intermediate gamma-MSH-LI, eluted between the position of mouse 16K fragment and human ACTH, and was demonstrated only in two ectopic ACTH-producing tumours. No gamma-MSH-LI emerged at the elution position of synthetic gamma 3-MSH. Affinity chromatography on concanavalin A-agarose revealed that a significant fraction (52-68%) of gamma-MSH-LI from human pituitary glands, ACTH-producing pituitary adenomas, and one ectopic ACTH-producing tumour bound to the column and was eluted with alpha-methyl-D-mannopyranoside. In two ectopic ACTH-producing tumours which contained big and intermediate gamma-MSH-LI, a relatively small fraction (27-35%) of gamma-MSH-LI bound to the column and was similarly eluted. These observations suggest that human gamma-MSH-LI is glycosylated and that there is an abnormality in the glycosylation of gamma-MSH-LI in some ectopic ACTH-producing tumours.

ACTH Syndrome, Ectopic↗
PubMed1981

Concomitant secretion of adrenocorticotropin, beta-endorphin, and gamma-melanotropin from perfused pituitary tumor cells of Cushing's disease: effects of lysine vasopressin, rat median eminence extracts, thyrotropin-releasing hormone, and luteinizing hormone-releasing hormone.

Regulation of secretion of ACTH-, beta-endorphin-, and gamma-melanotropin-like immunoreactivities (ACTH-LI, beta-EP-LI, and gamma-MSH-LI, respectively) was studied by using a perfused Sephadex column containing dispersed pituitary tumor cells obtained from three patients with Cushing's disease. Serial dilution of the perfusion medium gave lines parallel to the standard curve in each RIA for ACTH, beta-EP and gamma-MSH, suggesting that immunoreactive materials in the medium are immunologically indistinguishable from the authentic peptides. Gel exclusion chromatography of the medium revealed the existence of ACTH, beta-lipotropin (beta-LPH), beta-EP, and their possible precursor protein. gamma-MSH-LI consists of a major peak of big gamma-MSH eluted near the elution position of beta-LPH, suggesting the entire or nearly entire N-terminal portion of the precursor molecule. The addition of lysine vasopressin and rat median eminence extracts (MEE) to the perfusion system concomitantly enhanced the release of ACTH-LI, beta-EP-LI, and gamma-MSH-LI, although the dose-response relationship was clear-cut only in the case of MEE. TRH and LRH also elicited the concomitant release of these peptides in one patient, in whom combined administration of TRH and LRH significantly augmented plasma cortisol levels when studied preoperatively. The molar ratio of ACTH-LI to beta-EP-LI was approximately 1.0, whereas gamma-MSH-LI was about one fourth of ACTH-LI when compared on a weight basis. These results indicate that 1) ACTH-producing human pituitary adenomas concomitantly secrete ACTH, beta-LPH, beta-EP, and big gamma-MSH, and 2) lysine vasopressin, MEE, TRH, and LRH act directly on pituitary cells to stimulate the release of these peptides.

Adenoma↗
PubMed1981

Presence of dynorphin-like immunoreactivity in pheochromocytomas.

Using a highly specific and sensitive radioimmunoassay for dynorphin(1-13), dynorphin-like immunoreactivity (dynorphin-LI) was detected in two extramedullary pheochromocytomas and a medullary pheochromocytoma. The contents of dynorphin-LI of two extramedullary and a medullary tumors were 9.2, 2.2, and 34.0 pmole/g, respectively. Gel chromatographic studies of tumor extracts on Sephadex G-50 revealed a peak of dynorphin-LI eluting at the same position as dynorphin-LI contaminated in porcine ACTH extract (Sigma) and another portion of dynorphin-LI eluting in a range of molecular weights larger than that of dynorphin-LI in porcine ACTH extract. These results indicate the presence of dynorphin and possibly its precursor peptide(s) in pheochromocytoma.

Adrenal Gland Neoplasms↗